AP PhotoRoger Mayweather, Floyd Jr.'s trainer and uncle, works with the Grand Rapids native in the ring during a recent training session in Las Vegas.

When the issue arose last week of his nephew's layoff, which reaches 21 months tomorrow, Roger Mayweather blanched, then correctly pointed out how some of the greatest names in boxing history, alongside which his nephew compares favorably, overcame much more substantial respites.

Floyd Mayweather's labor day looms next week in a comeback bout against Juan Manuel Marquez that falls something short of his all-important potential showdown against Manny Pacquiao, and well beyond the sort of tuneup fight most in his position would have taken.

The Grand Rapids native has 12 rounds, in 12 days, to traverse the rust vs. rest canyon, while trying to shake off the former in the midst of a bout against a man renowned for his own mid-fight tweaks. As Marquez adjusts to Mayweather, Mayweather must adjust to both Marquez and himself.

There isn't anything easy about it.

Roger Mayweather fought steadily from 1981-99, and during his two-championship career took only one break as long as a full year, and then only at the very end.

He remains a rare student of boxing, however, and can recite some of the more -- and less -- successful comebacks by rote and rationale.

Essentially, fighters who build their legends as whirlwinds, then embark on comebacks after lengthy layoffs, generally find their dynamic fury difficult to recreate.

Those with more fundamental foundations -- a category into which Floyd Mayweather definitively falls -- have easier times of it.

That's why Mayweather may not be exactly the same fighter as before but should come far closer to it than naysayers might hope.

"The greatest fighters in the world have had layoffs," Roger Mayweather said. "What do you think Sugar Ray Leonard had? He had a 51/2-year layoff. He had two detached retina surgeries. And he still beat Marvin Hagler after being laid off 51/2 years. Sugar Ray Robinson was laid off three years and that's the greatest fighter on the globe. Ali was laid off three years.

"So Floyd ain't the only guy that's been laid off. Most of the greatest fighters in the history of boxing have one thing in common: They've been laid off."

Leonard actually had one fight in five-plus years before defeating Hagler, although the rest of the timelines essentially are accurate.

And so is this: Robinson spent several years losing and regaining championships after his comeback, against fighters who might not have touched him beforehand; Muhammad Ali did great things after his comeback, but undeniably was not the same after his draft-refusal layoff; and Leonard stretched his comeback too far and took some losses because of it.

Fury-fueled fighters have the biggest comeback problems.

Joe Louis' post-war comeback resulted in some good wins after one fight in four years, but a second comeback, induced by tax trouble, was not as successful and included two of his three losses, to Ezzard Charles and Rocky Marciano.

Mike Tyson's post-prison comeback began with some typical tuneups but he never was close to the same fighter after his rape conviction, was softened up in ugly losses to Evander Holyfield and Lennox Lewis, then later blown out by little-known Danny Williams and Kevin McBride.

Floyd Mayweather, at 32 years old, should not yet be in the position of challenging his 39-0 record via timeline.

Then again, Father Time treats people differently.

"Once I started boxing, I had to box a few times, you know, box four or five times," Floyd Mayweather said. "I still was looking good, I really wasn't taking no punishment. But about the fifth time I started boxing, I started looking real, real sharp, looking real, real good."

The rib injury that postponed the original July date was indicative of an athlete on the rebound, but if Mayweather falters against Marquez, the choice of comeback opponent will bear more responsibility than the down time.

"I don't think the two-year layoff is going to affect me," he said. "I feel fast, I feel strong and the timing is there."